This invention relates to a new safety tire for automotive vehicles.
Pneumatic tires for automobiles, trucks, and other automotive vehicles have been used for many years. While the first tires were made of a fairly porous rubber and had to be used in conjunction with an inner air chamber, tubeless tires were introduced in about 1950; these became standard in the automotive industry. Tubeless tires have a special lining on their inner surface, capable of retaining air under pressure. When a tire is punctured by a sharp object, for example, a nail, it loses air and is incapable of supporting the weight of the vehicle. The tire (or the inner chamber, if the tire is not tubeless) must then be repaired. However, often a puncture will occur at some distance from a service station where the repair can be performed. Since running flat would ruin the tire, the wheel must be replaced, and it thus is necessary to always carry a spare tire mounted on a wheel.
There are many persons, however, who are unable to change the wheel because of its size or weight. Changing a wheel at night or along a busy highway could be dangerous even to those able to handle the task. The spare wheel usually is carried in the trunk of an automobile, where it takes valuable storage space. If luggage is carried in the trunk, it often must be removed before the spare wheel can be reached. The ideal solution to the problem would be to have tires which either could not be punctured or, even if they are punctured, could run for a considerable distance without requiring immediate replacement or repair.
Various safety tires have been proposed in the past. Often, they are of double-chamber construction, wherein the inner chamber serves as a tire within a tire and is capable of supporting the weight of the vehicle for some distance. The prior art safety tires suffer from many shortcomings, the most common problems being (1) the difficulty in mounting both chambers on the same rim, and (2) the tendency of both chambers when flat to fall off the rim at even moderate speeds. Various such designs also caused considerble wheel balancing problems.
Furthermore, prior art double-chamber tires required fabric reinforcement of the inner chamber to render the chamber practically inextensible at operating pressures. This requirement necessitated complicated fabricating techniques. Some currently available safety tires are of single chamber construction and can run flat. This result is achieved by thickening the sidewalls, providing an internal lubricant, and installing the tires on special rims. The thickened sidewalls result in high operating temperatures, even when inflated, and in high cost.
There is, therefore, great need in the art for a safety tire that would be easy to install; when deflated, would remain seated on the rim during the operation of the vehicle; and, while deflated, would be capable of supporting the weight of the vehicle for a considerable distance at moderate speeds.